Electrical conversion system



May17, 1938.

c. J. YOUNG ELECTRICAL CONVERS ION SYSTEM Filed Jan. 51, 1935 u' I =3 Is H I Q P .I 3 w;

a L' T I I I V I I m Q! Q i I Q I; 'l L A I L l I L Q4 '7\ a 'q Q I O l"0 N w Q INVEN'IOR Charles J Young ATTORNEY Patented May 17, 19382,117,587

UNITED STATES PATENT OFFIiEE ELECTRICAL CONVERSION SYSTEM Charles J.Young, Haverford, Pa., assignor to Radio Corporation of America, acorporation of Delaware Application January 31, 1935, Serial No. 4,319

7 Claims. (01. 250-36) My invention relates to improvements inelecinverter being controlled from a constant or ref 11140941 ConversionSystems e Pa t cularly, erence A. C. voltage. Provision is made fortunto a system for synchronizing motors with a defi-- ing the variouscircuits in the system whereby nite control f q y. the output frequencyfrom the grid controlled My improved system is particularly adaptedgaseous discharge inverter can be changed selecfor facsimile work,systems for clock control, and tively to obtain any one of severalpredetermined similar devices wherein there is a rotating shaft tofrequencies to change the speed of the driving be locked in phase and insynchronism with a motor accordingly.

source of alternating current such as might be My invention resides inthe improved system obtained under control of a constant tuning fork andmethod of operation of the character heren.

or a piezo-electric standard. inafter described and claimed.

In the early development of facsimile, synchro- For the purpose ofillustrating my invention,

n'ism of the rotating shaft associated with or an embodiment thereof isshown in the drawing, forming part of the receiver scanner was obwhichis a simplified diagrammatic view of an tained by the so-called Hammondthermionic electrical conversion system constructed and 0pit brake orsimilar circuit. The Hammond system crating in accordance with myinvention. comprised an alternator mounted on the shaft In the drawing,the parts and circuits under referred to, which acted as a variable loadon the the bracket a comprise a conventional grid condliving Ot Varation 0f the load being Controlled gaseous discharge inverter suppliedwith trolled in accordance with the existing relation power from a 115volt D. C. line 9. The inverter 29 at any time between the alternatoroutput frecomprises a pair of grid controlled gaseous disquency and anincoming control frequency from charge inverter tubes i2 and id and tankcir the transmitter. While this method was successcuits l6 and I8.

ful, it required a substantial surplus of power in The tank circuit l6operates as an excitation the driving motor and the use of a speciallydecircuit for the tubes I2 and it, and comprises a 25 Signed alternator.transformer 20 and an adjustable capacitor 22.

Another method for synchronization comprised The capacitor 22 isadjusted by a switch device 24 the amplification of a control frequencyto a having the contacts 26, 28 and 30. power level sufhcient toactually drive the rotat- The tank circuit I8 is connected, as shown, to

so ing shaft of the receiver scanner by means of a constitute the outputcircuit of the converter 1 synchronous motor. This method was not usedtubes, and comprises a reactor 32 and a variable extensively because itrequired excessively large capacitor 34. The capacitor 34 is adjusted bya vacuum tubes in the amplifier, and was correswitch device 36 havingthe contacts 38, 40 and spondingly inefficient. 42.

With the foregoing in mind, it is one of the In operation, the gridcontrolled gaseous dis- 3.5 objects of my invention to provide animproved charge inverter apparatus operates to convert electricalconversion system in which several the direct current in the line IE) toalternating hundred watts of synchronous power for a motor current whichis taken from the reactor 32 by a can be easily and efficientlyobtained, without the supply line 44 which might supply a synchronous(.11,- necessity of using a surplus of power in the drivmotor 46 fordriving a facsimile receiver, syn- 4o ing motor, or specially designedequipment such chronous electric clocks 48, or other like devices. as analternator or an amplifier comprising ex- For the purpose of controllingthe frequency cessively large vacuum tubes. of operation of the gridcontrolled gaseous dis- Another object of my invention is to providecharge inverter, a conventional temperature-conii) an, improved systemof the character referred to trolled tuning fork, designated by thereference wherein provision is made for obtaining selecnumeral 50,operates to develop control signals tively several desired synchronousspeeds of the at practically a constant frequency. A fork and drivingmotor without the employment of the associated circuits which might besatisfacclutches, elaborate and costly gear boxes, or tory for thispurpose are disclosed in detail in 50 other mechanical devices, asheretofore. Patent No. 1,937,583, issued December 5, 1933 to 60 Otherobjects and advantages will hereinafter E. B. Norrman. pp The parts andcircuits under the bracket 1) In accordance with my invention, a gridconcomprise a control amplifier for the inverter trolled gaseousdischarged inverter operates to apparatus a. drive a synchronous motor,the frequency of the The control signals from the fork device 5' 55 aresupplied by means of a transformer 52 to the grid of a tube 54.Considering a specific case, the tube 54 and a tank circuit 55,associated therewith, are adjusted to oscillate at approximately 60cycles. The circuit 56 comprises a reactor 58 and a variable capacitoriii]. The capacitor (if! is adjusted by a switch device 62 having thecontacts 6 -3, 66 and 68.

The reference numeral i0 designates a plate choke associated with thetube 54, i2 a feed-back capacitor, and i l a grid-leak resistance. Thetube 54 is in a normally oscillating condition due to the adjustment ofits circuit constants.

Considering a specific case, the fork device 58 will be said to supplycontrol signals at a constant rate of 480 per second, and the switch 62will be considered as being on the contact 64, in which case adjustmentis such that the tube 54 will oscillate at approximately 60 cycles. Thistube, under control of the signals from the fork device 58, willmaintain operation at exactly 60 cycles, that is, at one-eighth of thefrequency of 480 cycles of operation of the fork device.

The 60-cycle Voltage from the tube 54 is transferred by a transformer 16to the grids of ampli-- fier tubes 78 and Bil, connected in push-pull.

The bias voltage on the tubes 54, T8 and 80 is taken from a resistance82.

For simplicity, the heater circuits for the various tubes have not beenshown.

With the switches 26 and 36 on the contacts 26 and 38, respectively, thegrid controlled gaseous. discharge is adjusted to oscillate atapproximately 60 cycles, and, under control of the constant 50-cyclevoltage supplied by the tubes l1! and Bil, will oscillate or lock in atexactly 50 cycles. The motor 66, clocks and any other similar deviceswhich might be supplied from the line 44, will, therefore, operate insynchronism with the control frequency supplied by the fork device 56.That is, with the adjustments specified, the voltage frequency in theline 4% will be one-eighth of the frequency of vibration of the tuningfork or other vibratory member of the frequency standard 55, and themotors supplied from the line 4% will, accordingly, run con stantly at1800 R. P. M.

When the switches 24, 36 and 52 are on the second taps 22, i and 56,respectively, the adjustments are such that the tubes E2, E4 and 54 willoscillate approximately at 80 cycles, that is, approximately at thesub-multiple of 6 of the fork frequency of 489 cycles. The tube 54,under control of the signals from the fork device 50, will be locked infor operation at exactly 80 cycles. The tubes 52 and M, under control ofthe 80 cycle voltage from the tubes 18 and 89, will also be locked infor operation at exactly 80 cycles. The synchronous motors supplied fromthe line 44 will then operate constantly at 24i00 R. P. M.

"With the switches 24, 35 and E2 on the third contacts til, 42 and 68,respectively, the tubes l2, M and 5 will be adjusted to oscillateapproximately at cycles, or at the sub-multiple l of the fork frequencyof 480 cycles. Under control of the signals from the fork device 511,these tubes will be locked in for operation at exactly 120 cycles. Themotors supplied from the line a l will then operate constantly at aspeed of exactly 36-30 P. M.

Other divisions or sub-multiples of the constant frequency of operationof the standard may be obtained by changing the adjustments, as will bewell understood.

It is contemplated to actuate or adjust the switches 24, and 62 from acommon shaft 84, which arrangement gives the equivalent of thespeed-change lever associated with the gearboxes used heretofore forspeed control in facsimile systems.

From the foregoing it will be seen that I have provided an improvedelectrical conversion system, by which one or more synchronous motorsmay be made to operate at different speeds, in synchronism with afrequency standard. A speed change is effected merely by adjustment ofone or more electrical circuits, and without resource to clutches,gears, or other mechanical devices. improved system makes possible theuse of clock control system comprising standard synchronous Clocks,Where only direct current power is available, such in large buildingsand aboard ship. That is, by my improved system it is possible toefficiently obtain a GO-cycle power supply of great constancy in placeswhere only direct current power is available.

It will be understood that various modifications, within the conceptionof those skilled in the art, are possible without departing from thespirit of my invention or the scope of the claims.

I claim as my invention:

1. In. an electrical conversion system, a pair of grid controlledgaseous discharge inverter tubes connected in push-pull relation andnormally oscillating, means operable to oscillate at a definitefrequency independently of operating action of said tubes to developcontrol signals, a circuit connected with said tul es for causing thesame to operate substantially at a sub-multiple of said definitefrequency, and means connecting said first-named means and said tubesand operating to supply the latter with said control signals.

2. In an electrical conversion system, grid controlled gaseous dischargeelectron inverter means for converting direct current to alternatingcurrent, an adjustable circuit connected with said means for causing thesame to oscillate selectively at different frequencies, means operableto oscillate at a definite frequency independently of op-- eratingaction of said inverter means to develop control signals, meansconnecting said oscillatory means and said inverter means to supply thelatter with said signals, and means for adjusting said circuit to causesaid inverter means to operate selectively at different desiredsub-multiples of said definite frequency.

3. In an electrical conversion system, grid controlled gaseous dischargeelectron inverter means for converting direct current to alternatingcurrent, said means normally oscillating, means for producing electricaloscillations of fixed frequency independently of the operating action ofsaid irverter means to develop control signals, means connecting saidoscillatory means and said in-- verter means to supply the latter withsaid nals, a plurality of adjustable circuits connected respectivelywith said connecting means and said inverter means to control thefrequency of operation thereof, means common with respect to saidcircuits for adjusting the same to cause said inverter means to operateselectively different desired sub-multiples of said definite frequency.

4. In an electrical conversion system, a source of control signals ofsubstantially constant frequency, said source comprising a vibratorymemher having a natural period of vibration corresponding to saidconstant frequency, normally oscillating grid controlled gaseousdischarge apparatus for converting direct current to alternatingcurrent, means for adjusting said apparatus to respond at a frequencywhich is substantially a sub-multiple of the frequency of vibration ofsaid constant frequency, means interposed between said constantfrequency source and said converter, means for supplying said controlsignals thereto, and a load circuit for utilizing the producedcontrolled alternating current.

5. In an electrical conversion system, a source of control signals ofsubstantially constant frequency, said source comprising a vibratorymemher having a natural period of vibration corresponding to saidfrequency, normally oscillating grid controlled gaseous dischargeapparatus for r converting direct current to alternating current,

a tuned circuit connected with said grid controlled gaseous dischargeapparatus, means for adjusting the tuned circuit to approximately asub-multiple of the frequency of vibration of said member and meansinterposed between said con trol means and said apparatus for supplyingsaid apparatus with said control signals, and a load circuit to utilizethe produced controlled alternating currents.

6. The method of converting direct current energy to alternating currentenergy of substantially constant frequency which comprises the steps ofdeveloping constant frequency energy, deriving energy of a sub-multiplefrequency from said developed constant frequency energy, controlling anormally oscillating ionic discharge to produce alternating currentenergy from direct current energy, and controlling the frequency of theproduced alternating current by the derived sub-multiple frequencyenergy.

'7. In an electrical conversion system, a source of constant frequencyenergy, means for deriving sub-multiple frequency energy from saidsource, a push-pull normally oscillating gridcontrolled gas dischargetube oscillator having an output circuit, means for controlling thefrequency of said oscillator by the derived sub-multiple frequencyenergy, and means for simultaneously changing the sub-multiple derivedenergy and the natural period of the oscillator, which maintains controlof the frequency of the energy in the output circuit of the oscillator.

CHARLES J. YOUNG.

